is there anyway that you can SUM all the values from column C and create an Mathcad solution?
You are just about to switch from Excel calculation sheets to Mathcad, right?
See the attached for doing what you have demanded without using and embedding Excel, which I consider an anachronism anyway for this task.
I think you should forget about thinking in rows and columns and cell formulas but rather think the way you would use your formulas in a more natural way. I know, after using Excel for some years one begins to believe that pure numbers in a grid without any units, with an awkward way to name cell ranges and with hidden formulas is natural, but it sure isn't.